Whoever added "I Was Trash, I Am Trash, I Will Be Trash" as an alternate title is a genius.
This is not a well-written story. It timeskips without notice, adds then drops characters and plot points freely and suddenly, abuses coincidences like an alcoholic father with a tire iron, and there's some other stuff where I can't decide if it doesn't make sense because it's just nutty writing or because I don't know the culture.
However, it's readable for two reasons: the girls are hot. And the MC - dear god, this guy is everything you should never write in an MC. He's Mr. perfect, with OP martial arts and an unflappable attitude. But somehow, it's really quite fun to watch him waltz effortlessly through his life, flattening everything in his way and quipping with an ever-expanding set of women who are quite interested in him. I'm not sure why he's fun to watch.